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Surgery Before Birth Improves Spina Bifida Outcomes

Surgical repair of a spinal birth defect before birth, rather
than after, can improve mobility and reduce the risk of serious
complications, a new study found. The outcomes were so positive
that the clinical trial was stopped early. However, the procedure
does carry some risks, such as preterm birth.

The birth defect, called myelomeningocele, is the most serious
form of spina bifida, a condition in which the spinal column fails
to close around the spinal cord. With myelomeningocele, the spinal
cord protrudes through an opening in the spine of the early embryo.
After birth, the disorder often results in weakness or lower-limb
paralysis. It leads to death in about 10% of affected infants.

Newborns with myelomeningocele typically undergo surgery to place
the cord back into the spinal cavity and seal the opening with
sutures. But studies in animals suggested that surgery in the womb
might yield better outcomes.

To investigate, a multi-site team of scientists enrolled more
than 150 pregnant women in a clinical trial. About half were randomly
assigned to have surgery to close the spinal defect in their unborn
child before the 26th week of pregnancy. The other women had the
surgery performed on the child after birth. The study was funded
by NIH’s Eunice Kennedy Shriver National Institute of Child
Health and Human Development (NICHD).

As described in the February 9, 2011, online edition of the New
England Journal of Medicine, by 1 year of age, infants who
had received prenatal surgery were less likely to need a follow-up
procedure to divert, or shunt, fluid away from the brain. About
65% of infants in the prenatal surgery group needed a shunt,
compared to 92% in the post-natal surgery group.

All of the babies had a condition before birth called hindbrain
herniation, in which the base of the brain is pulled into the spinal
canal. However, by 1 year of age, one-third of the children (36%)
who had prenatal surgery no longer had evidence of hindbrain herniation,
compared to 4% in the postnatal surgery group.

By 2½ years of age, the prenatal surgery had resulted in
significant improvements to both mental and motor functions. Although
the ability to walk depends on the location of the spinal defect,
children in the prenatal surgery group were about twice as likely
to be able to walk without orthotics or crutches (42%) as children
who had received postnatal surgery (21%).

Scientists originally intended to enroll 200 expectant mothers
in the study, but the trial was stopped early because of the benefits
seen in children who received prenatal surgery. Some complications,
however, were more likely in the prenatal surgery group. These
babies were more likely to be born preterm, and mothers who had
the surgery during pregnancy were more likely to have uterine dehiscence,
a thinning or tearing at the surgical incision in the uterus.

"In spite of an increased risk for preterm birth, children
who underwent surgery while in the uterus did much better, on balance,
than those who had surgery after birth," says NICHD Director
Dr. Alan E. Guttmacher. "However, caution is advised. Because
the surgery is highly specialized, it is best undertaken in facilities
with staff having experience in the procedure."